Short answers, pulled from the story.
Captain Ahab is the monomaniacal captain of the whaling ship Pequod in Herman Melville's 1851 novel Moby-Dick. He is driven by an obsessive desire for revenge after the white whale Moby Dick bit off his leg on a previous voyage, and his hunt for the whale ends in the destruction of the Pequod and his own death.
Ahab throws his harpoon and strikes Moby Dick during a final three-day chase, but the line wraps around his neck and drags him beneath the sea when the whale dives. The Pequod sinks with the loss of all hands aboard.
Moby Dick bit off Ahab's leg on a whaling voyage prior to the novel's events, leaving him with a prosthetic leg made from ivory. The leg slots into shallow holes bored into the Pequod's deck so Ahab can steady himself at sea, and it includes a small flat patch he uses as a slate for navigational calculations.
Melville created Ahab under the influence of Samuel Taylor Coleridge's lecture on Hamlet and drew heavily on Shakespeare, John Milton's Paradise Lost, and figures from Greek myth including Oedipus, Prometheus, and Narcissus. Biographer Leon Howard called Ahab "a Shakespearean tragic hero, created according to the Coleridgean formula."
Ahab's name derives from the Hebrew for "father's brother" and alludes to the biblical King Ahab of the Books of Kings, described as doing "evil in the sight of the Lord above all that were before him." Melville used this association to foreshadow his captain's tragic end and his idol-worshipping defiance of God.
J. M. Barrie modeled Captain Hook directly on Captain Ahab from Moby-Dick, replacing Ahab's obsession with a white whale with Hook's fixation on a crocodile. Ahab is identified as the most famous influence on Hook's character in popular culture.